count

Daria Barysheva

Definition

Returns the number of rows in the table. As calculating can take a long time, the current count is shown every 1000 rows by default — this interval can be changed by setting the input parameter INTERVAL.

Scan caching is also enabled. The default cache size is 10 rows — this value can be changed by setting the input parameter CACHE. If your rows are small in size, you can increase its default value.

Usage

  • The basic syntax:

    count '[<namespace_name>:]<table_name>'[,
      COLUMNS => <columns_array[]>][,
      STARTROW => '<start_row_key>'][,
      STOPROW => '<stop_row_key>']

  • Using optimization parameters:

    count '[<namespace_name>:]<table_name>'[,
      INTERVAL => <interval_value>][,
      CACHE => <cache_value>]

  • Using filters:

    count '[<namespace_name>:]<table_name>',
      {FILTER => "<filter_description>"}
Arguments
Parameter Description

namespace_name

A namespace name

table_name

A table name

columns_array

An array of strings specified in the format '<column_family>:<column_qualifier>', where <column_family> — a column family name; <column_qualifier> — a column qualifier

start_row_key

A start value for searching row keys

stop_row_key

A stop value for searching row keys

interval_value

An interval for showing the intermediate result

cache_value

A cache size

filter_description

A filter used for searching the table cells

Examples

Counting a number of all rows in the table

hbase(main):024:0> count 't4'
1 row(s)
Took 0.0175 seconds
=> 1

Counting a number of rows having the specified column

hbase(main):029:0> count 't4', COLUMNS => ['cf1:1']
0 row(s)
Took 0.0079 seconds
=> 0
hbase(main):030:0> count 't4', COLUMNS => ['cf1:c1']
1 row(s)
Took 0.0053 seconds
=> 1

Counting a number of rows matching the defined filter

hbase(main):027:0> count 't4', {FILTER => "ValueFilter(=, 'regexstring:value*')"}
1 row(s)
Took 0.0346 seconds
=> 1

Counting a number of rows having the keys between STARTROW and STOPROW

hbase(main):033:0> count 't4', COLUMNS => ['cf1:c1'], STARTROW => 'r1', STOPROW => 'r2'
1 row(s)
Took 0.0064 seconds
=> 1

Using INTERVAL and CACHE parameters

hbase(main):025:0> count 't4', INTERVAL => 100000, CACHE => 1000
1 row(s)
Took 0.0112 seconds
=> 1
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